I would absolutely take H/H for this pet for split then either heal with Drain Blood or grind them out with drain power and grind out with slot 1 abilities. Nice mixup pet against the humanoids in pvp. P/P would be king for pve, this can solo a few trainers with its crazy sustain.

Update: As of 11/7 this pet no longer has split unfortunately. It seems Blood Boil is now just a slime with no unique abilities outside of drain power. S/S would probably be the better breed now.

Supposedly comes in every possible breed. I personally have H/H, H/S, H/P and P/S sitting in my bags and have no idea what to keep and what to toss. Split is HP based, so perhaps H/H or any of the H/* breeds?